OK, guys, here is the definitive answer. It appears in a book - The Royal Navy in Old Photographs (1975) - by Wifrid Trotter, a well-respected Naval Historian.
"In 1902 Russia sent the cruiser Askold, the only five-funnelled warship in the world, to the Persian Gulf; the Persians were considerably impressed. Britain ordered HMS Amphitrite, then on her way to the China Station, to proceed to Muscat. Amphitrite, an 11,000-ton first-class protected cruiser, was larger than Askold but had only four funnels, so the Captain rigged two extra funnels of wood and canvas and led smoke to them. Thus prestige was restored!"
However, "Surface Line" has come up with a genuine six-funneled RN ship, so it's over to him for the next question.
Happy New Year!
Rick